[SOLVED] Questins about creating a QML component using c++

[terietor]

Hello,

I want to make a component which requires to use c++. I have read the docs about
creating components via c++ but i have some questions.

@class HelloQML : public QObject {
//foo
bool setHelloMessage(A *a_hello, B *b_hello);//question no1
C * helloMessage();//question no2
//will the above work?
Q_INVOKABLE void doHello(char a, QString b, QString *c);//question no3
}@

@import foo

HelloQML {

helloMessage: {
//Question no1
//what should i add here??
}
//Question no3
//will this work?
doHello('a', "aa", "aaa");
}@

A,B,C are my classes which doesn't derive from QObject and I haven't add to them any QML relative code.

thanks in advance

[sierdzio]

in order for any functions to be available in QML, you have to use either Q_INVOKABLE or Q_PROPERTY. So, "questions" 1 and 2 will not work. You are trying to use those methods as properties, which is wrong. You'll have to declare a property, and then add getter, setter methods, and a notification signal.

About question 3 - this will also fail. You are trying to invoke a JS/C++ method directly in QML, which is not supported. You can invoke methods in assignments (like "height: myMethod(foo)") or in slots. So, here, for it to work, you'll have to use:
@
// inside HelloQML
Component.onCompleted: doHello('a', "aa", "aaa");
@

Also, your import statement is wrong. It has to specify version number, IIRC.

[terietor]

[quote author="sierdzio" date="1327128947"]in order for any functions to be available in QML, you have to use either Q_INVOKABLE or Q_PROPERTY.
[/quote]

My mistake,I didn't mention about the existance of a Q_PROPERTY, before setHelloMessage there are

@
Q_OBJECT
Q_PROPERTY(...)
@

[quote]
About question 3 - this will also fail. You are trying to invoke a JS/C++ method directly in QML,[/quote]

Correct.This was wrong

I wanted to know if my code will work from the point of view that classes A,B,C doesn't derive from QObject.

[sierdzio]

[quote author="Giorgos Tsiapaliwkas" date="1327183176"]
I wanted to know if my code will work from the point of view that classes A,B,C doesn't derive from QObject.
[/quote]

I don't think I've ever tried doing that, so I can't give you a definite answer. IIRC, as long as QVariant can work with these classes, you can use them in QML - C++ communication.

[terietor]

[quote author="Giorgos Tsiapaliwkas" date="1327072363"]Hello,

@
bool setHelloMessage(A *a_hello, B *b_hello);//question no1
@

@import foo

HelloQML {
onSomething:{
helloMessage: {
//what should i add here??
//my setter has two parameters.
}
}@
[/quote]

Does anyone know what I should add??

Will this work?

@import foo

HelloQML {
onSomething:{
helloMessage: {
A:.....
B:.....
}
}@

[sierdzio]

Properties can have only one parameter. They should represent getters and setters directly. I'm afraid your code is wrong again: you open a JavaScript block after "onSomething", which would any QML assignment inside invalid (like on lines 5., 6., and 7.).

Here's a tip that would probably help you most: go ahead and try. Think of a simple, example application and code it to get basic experience. This would make solving this problem a lot easier for you, and also will be a source of fun.

[terietor]

thank you

I will mark it as solved

[Punit_Tak]

Hello Sierdzio, your suggestions and tips helped me too. I would like learn from you if can start any forum related to Qt Quick and C++ integration. Nicely explained. Thanks a ton.

Hello Giorgos, Thanks for asking your doubt, it clears my doubt too.

Thanks and regards,
Punit Tak